style.css

.modal-contenido{
    background-color:#15496E;
    color: white;
    width:300px;
    padding: 10px 20px;
    margin: 10% auto;
    position: relative;
    border-radius: 5px;
    padding: 40px 30px;
  }
  .modal{
    background-color: rgba(0,0,0,.8);
    position:fixed;
    top:0;
    right:0;
    bottom:0;
    left:0;
    opacity:0;
    pointer-events:none;
    transition: all 1s;
    z-index: 999;
  }
  #miModal:target{
    opacity:1;
    pointer-events:auto;
  }
  
  #miModal:target{
    opacity:1;
    pointer-events:auto;
  }
  
  .btn_cerrar{
    text-decoration: none;
    background-color: #15496E;
    /*border-radius: 50%;*/
    padding: 5px 8px;
    font-weight: bolder;
    position: absolute;
    top: 15px;
    right: 15px;
    color: white;
  }